Aperture stop laser warning system based on four-quadrant detection

Abstract

The utility model discloses a kind of aperture diaphragm laser warning systems based on four-quadrant detection, including aperture diaphragm, protective window, four-quadrant detector and processing board, the aperture diaphragm is located in front of detector photosensitive surface, and spacing is set between the two;The aperture diaphragm diameter is not greater than 1 / 2 of detector diameter, for limiting incident spot size and field of view range, realize the angle detection of laser in ±50 ° linear field of view;Aperture diaphragm is embedded in protective window, for protecting detector from environmental damage;The input end of four-quadrant detector is connected to the input end of processing board, and the processing board includes amplification circuit, A / D conversion circuit and processor, the input end of amplification circuit is connected to the output end of four-quadrant detector, and the output end of amplification circuit is connected by A / D conversion circuit and processor input end.

Description

Technical Field

[0001] This utility model relates to the field of laser alarm technology, and in particular to an aperture stop laser alarm system based on four-quadrant detection. Background Technology

[0002] Currently, most mainstream laser warning systems employ wide-angle detection or narrow-field-of-view stitching schemes, which suffer from problems such as large energy attenuation, low sensitivity, complex structure, high cost, and difficult assembly and adjustment. Wide-angle detection schemes utilize area array detectors in conjunction with fisheye lenses to achieve large field-of-view coverage, but are limited by optical system energy attenuation and narrow-band filters, resulting in a narrow dynamic range and saturation. Narrow-field-of-view stitching schemes achieve 360° coverage through multiple optical windows, but require a large number of windows, have a complex structure, are costly, and suffer from blind spots and response delays.

[0003] The wide-angle detection laser alarm scheme employs a multi-element area array photodetector, such as a visible light CCD or a mid-to-long-wave infrared focal plane array, matched to the wavelength of the received laser, combined with a narrowband filter to form the receiving unit; a staring wide-angle or "fisheye" optical imaging receiving system covers the entire alarm field of view. Because this scheme uses a narrowband filter, the detection band is narrow and the dynamic range is small; it will lose its alarm capability once the device's saturation threshold is exceeded.

[0004] Narrow field-of-view stitched laser warning system employs the principle of circumferentially setting a large number of optical windows. Typically, these windows are stitched together to form a 360° detection field of view, as illustrated in the diagram below. Figure 1 As shown, a central sensor is located at the highest point, capable of receiving laser signals from any direction to determine the arrival of the laser. N direction-finding optical windows are evenly distributed along the circumference of the hemisphere. Each window is responsible for detecting lasers in a specific direction, and the fields of view of adjacent windows overlap to eliminate blind spots. This scheme, due to its simple structural layout, has gradually gained application in laser warning equipment. However, the large number of detection windows in this scheme results in high cost and difficult assembly and adjustment, presenting unavoidable drawbacks for mass production. Utility Model Content

[0005] The purpose of this invention is to provide an aperture stop laser alarm system based on four-quadrant detection, which can solve the problems of complex structure, low accuracy and high cost in the existing technology, and realize laser detection and alarm with large field of view, high accuracy, lightweight and low cost.

[0006] The technical solution adopted in this utility model is as follows:

[0007] A laser alarm system based on four-quadrant detection with an aperture stop includes an aperture stop, a protective window, a four-quadrant detector, and a processing board. The aperture stop is located in front of the photosensitive face of the detector, with a spacing between them. The diameter of the aperture stop is no greater than 1 / 2 of the detector diameter, used to limit the incident light spot size and field of view, enabling angle detection of laser within a ±50° linear field of view. The aperture stop is embedded in the protective window to protect the detector from environmental damage. The output of the four-quadrant detector is connected to the input of the processing board. The processing board includes an amplifier circuit, an A / D conversion circuit, and a processor. The input of the amplifier circuit is connected to the output of the four-quadrant detector, and the output of the amplifier circuit is connected to the input of the processor through the A / D conversion circuit.

[0008] The amplifier circuit uses an SF603 amplifier, and in specific use, it includes a peripheral circuit consisting of corresponding resistors and capacitors to amplify the weak signal from the detector.

[0009] The A / D conversion circuit uses a B128S module, which can acquire 0~5V input signals.

[0010] The distance between the aperture stop and the detector is denoted as L, where L = 0.5 * (Dd) * cot (A / 2), and angle A is the total field of view of the system, D is the diameter of the detector, and d is the diameter of the aperture stop.

[0011] The processor described above adopts a combined MCU and FPGA processor architecture.

[0012] This invention achieves high-precision laser alarm with a large field of view through a four-quadrant detection + aperture stop limiting the field of view scheme. Specifically, a protective window and an aperture stop are placed in front of the photosensitive face of the detector, enabling angle detection of incident lasers within a ±50° linear field of view. The diameter of the aperture stop is less than or equal to half the diameter of the detector. Further, the four-quadrant detector converts the light spot energy into a proportional photoelectric signal based on the photoelectric effect and outputs it. A signal amplification circuit then amplifies the photoelectric signal, which is then converted into a digital signal by an A / D converter. The MCU and FPGA process and analyze the digital signal output from the A / D converter to calculate the azimuth information of the incident laser and output the azimuth and elevation angle of the incoming laser. Therefore, the laser alarm based on aperture stop using four-quadrant detection has advantages such as simple structure, large field of view, and high angle measurement accuracy, and has broad application prospects in the field of laser alarm. Attached Figure Description

[0013] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0014] Figure 1 This is a schematic diagram of existing technology;

[0015] Figure 2 This is a schematic diagram of the structure of this utility model;

[0016] Figure 3 This is a schematic diagram of the present invention. Detailed Implementation

[0017] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0018] like Figure 1 , 2 As shown in Figure 3, this utility model comprises an aperture stop 1, a protective window 2, a four-quadrant detector 3, and a processing board. (The four-quadrant detector described in this application is a GD43111Y or GD4316Y type detector; the schematic diagram is shown in Figure 3.) Figure 3 As shown, the aperture stop (located in front of the detector's photosensitive face) has an opening angle that does not affect the entry of light from the edge of the field of view, and its diameter is no greater than 1 / 2 of the detector's diameter. It is used to limit the size of the incident light spot and the field of view, enabling angle detection of the laser within a ±50° linear field of view. The protective window protects the detector from environmental damage. In actual use, different anti-reflection coatings are applied to the protective window depending on the sensitivity of the detector; the thickness is not limited, as long as the structural dimensions are suitable. The four-quadrant detector converts the light spot energy into four electrical signals. After amplification and A / D conversion, the signals are processed by an MCU+FPGA, and the laser incident angle is calculated using a sum-difference-amplitude algorithm. Since the four-quadrant detector is an existing product, the methods and processes involved in its calculations are prior art and are not within the scope of protection of this application. This application has a compact overall structure, eliminating the need for mechanical scanning or multi-window splicing, significantly simplifying the optical structure and assembly process.

[0019] In actual use, the aperture stop diameter of this application is: d≤0.5*D, where D is the detector diameter and d is the aperture stop diameter; the distance L between the aperture stop and the detector is optimized according to the field of view and the spot offset to ensure that the spot always falls within the effective area of ​​the four quadrants within the set field of view, L=0.5*(Dd)*cot(A / 2), where angle A is the total field of view of the system; the protective window and the aperture stop are sealed by adhesive curing to avoid stray light interference.

[0020] This scheme uses a four-quadrant photodetector to determine target deviation. A four-quadrant photodetector consists of a circular position-sensitive device divided into four equal parts, with one detector in each quadrant. The four-quadrant photodetector is located behind the aperture stop. The laser signal reflected from the target S is imaged by the aperture stop, forming a light spot S' on the four-quadrant photodetector. The center of the four-quadrant photodetector is the optical axis. When the light spot is exactly on the central optical axis, the photoelectric signal amplitudes output by the four photodetectors are the same. When the light spot S' deviates from the optical axis, the amplitudes of the photoelectric signals output by the four photodetectors are different. By comparing the different amplitudes of each signal, the quadrant in which the light spot falls can be calculated, and the deviation error of the target S can be further calculated.

[0021] This invention not only boasts a simplified structure—requiring only a single optical channel and eliminating the need for multi-window splicing or complex lens assemblies, significantly reducing size, weight, and cost—but also achieves high-precision angle measurement: based on a four-quadrant detector and a difference-to-amplitude algorithm, it enables high-precision angle calculation within the field of view. Furthermore, it possesses strong anti-interference capabilities: the aperture stop effectively suppresses stray light, improving the signal-to-noise ratio and anti-false alarm capability. Moreover, this invention is applicable to a wide wavelength range: covering the 532nm~1550nm laser band, adapting to various battlefield laser threats.

[0022] Currently, there is no laser alarm system that can replace this solution under the same conditions of field of view, accuracy, size, and cost. Other solutions, such as multi-window splicing or mechanical scanning, cannot simultaneously achieve structural simplification and performance improvement.

[0023] In the description of this invention, it should be noted that directional terms such as "center", "lateral", "longitudinal", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", and "counterclockwise" indicate the orientation and positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. They should not be construed as limiting the specific protection scope of this invention.

[0024] It should be noted that the terms "comprising" and "having" and any variations thereof in the specification and claims of this application are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units is not necessarily limited to those steps or units that are explicitly listed, but may include other steps or units that are not explicitly listed or that are inherent to such process, method, product, or device.

[0025] Note that the above description is merely a preferred embodiment and application of the technical principles of the present invention. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and various obvious changes, readjustments, and substitutions can be made without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the specific embodiments described herein, and may include many other effective embodiments without departing from the concept of the present invention. The scope of the present invention is determined by the scope of the appended claims.

Claims

1. An aperture stop laser warning system based on four-quadrant detection, characterized in that: The system includes an aperture stop, a protective window, a four-quadrant detector, and a processing board. The aperture stop is located in front of the photosensitive face of the detector, with a spacing between them. The diameter of the aperture stop is no greater than 1 / 2 of the detector diameter, used to limit the incident light spot size and field of view, enabling angle detection of laser light within a ±50° linear field of view. The aperture stop is embedded in the protective window to protect the detector from environmental damage. The output of the four-quadrant detector is connected to the input of the processing board. The processing board includes an amplifier circuit, an A / D conversion circuit, and a processor. The input of the amplifier circuit is connected to the output of the four-quadrant detector, and the output of the amplifier circuit is connected to the input of the processor through the A / D conversion circuit.

2. The aperture stop laser alarm system based on four-quadrant detection according to claim 1, characterized in that: The amplifier circuit uses an SF603 amplifier, and in specific use, it includes a peripheral circuit consisting of corresponding resistors and capacitors to amplify the weak signal from the detector.

3. The four-quadrant detector based aperture stop laser warning system of claim 2, wherein: The A / D conversion circuit uses a B128S module, which can acquire 0~5V input signals.

4. The four-quadrant detector based aperture stop laser warning system of claim 3, wherein: The distance between the aperture stop and the detector is denoted as L, where L = 0.5 * (Dd) * cot (A / 2), and angle A is the total field of view of the system, D is the diameter of the detector, and d is the diameter of the aperture stop.

5. The four-quadrant detector based aperture stop laser warning system of claim 1, wherein: The processor adopts a combined MCU and FPGA processor architecture.

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